Photoelectric sound reproducer



Am 1941 J. F. WEIN 2,238,143

PHOTOELECTRI C S OUND REPRODUCER Filed Sept. 30, .1939

Enventor ciMF/f'ira Gttorneg Patented Apr. 15, 1941 PHOTOELECTRIC SOUNDREPRODUCER .iohn F. Wein, Indianapolis, Ind, assignor to RadioCorporation of America, a corporation of Delaware Application September30, 1939, Serial No. 297,261

2 Claims. (01. 179-1003) This invention relates to a photoelectric soundreproducer and more particularly to a mount for the optical systemdirecting sound modulated light from the translation point to thephotoelectric :cell in a push-pull sound reproducer.

There have heretofore been constructed many types of push-pull soundreproduction apparatus, some adapted for separate sound tracks andothers adapted for adjacent portions of the same sound track. At thepresent time, the type of push-pull reproducer which is foundcommercially acceptable is adapted for use with two oppositely phasedhalves of the sound record on the standard sound track area, the twohalves being arranged side by side and with a very narrow space of theorder of a few thousandths of an inch between them.

In the reproduction of such a sound record a fine line of light having awidth of the order of ths of an inch is directed upon the sound trackand the light passing through the sound track is divided in accordancewith the portions thereof through which it passes, the portion from onehalf of the sound track being directed to one cathode of a push-pullphotocell and the portion from the other half of the track beingdirected to the other cathode hereof. An appropriate optical system foraccomplishing this result is shown, for example, in Dimmick Patent2,164,735.

The mounting of such an optical system is somewhat difiicult as theentrance pupil thereof must be accurately aligned with the opticalsystem directing light upon the film and the optical system must be solocated laterally of the film that the division of light between the twophotocell cathodes accurately corresponds with the division between thetwo halves of the sound track.

The apparatus of the present invention provides a mounting for rigidlysecuring an optical system of the type described in proper relation toboth the film and the photocell and at the same time is provided withsuch adjustments that the optical system may be adjusted into exactposition and then securely bolted in adjustment.

One object of the invention is to provide an improved push-pull opticalsystem.

Another object of the invention is to provide an improved adjustingmechanism for an optical system mount.

Another object of the invention is to provide an improved means forsecuring an optical system in predetermined relation to both a soundrecord film and a photocell.

Other and incidental objects of the invention will beapparent to thoseskilled in the art from a reading of the following specification and aninspection of the accompanying drawing in which Figure 1 is a side viewof my improved method showing the film drum photocell mount and opticalsystem as mounted in a sound-head;

Figure 2 is a view taken from the right-hand side of Fig. 1; and

Figure 3 is a section through the mounting bracket on the line 3-3 ofFig. 2.

Referring first to Figure 1, which shows a portion of the side view of asoundhead of the general type shown in Loomis et al. Patent 2,019,147,the filirr F passes downwardly from the picturehead and around the filmdrum l0 which supports it with the sound track overhanging the edge ofthe drum in alignment with the optical system I I which focuses a narrowtransverse line of light upon the film at the translation point. Sincethe other mechanical features of the soundhead are described in theaforesaid patent, a detailed description of them is unnecessary. Lightpassing through the film F at the translation point is received by theoptical system generally indicated at l3 which directs it in the form ofa separated beam onto the two cathodes of a pushpull photocell locatedwithin the photocell shield H2. The photocell and the details ofconstruction of the optical system are not shown here inasmuch as theyare shown in the aforesaid Dimmick patent.

The optical system bracket is mounted on a member which is made integralwith the photocell base M. This integral member consists of a portion [5which is provided with a flat face against which the bracket member I6fits. This bracket member IS in turn carries a member I1 which is madeintegral with the optical system casing. The member IT is movable towardand away from the film F for the purpose of focusing and this movementis accomplished by means of the cam screw 18. This cam I8 has oneportion 20 which fits rotatably into the bracket i6 and. anothercylindrical extension ZI which fits into -a slot 22 in the member IT.The member I1 is also held to the member l6 by the cap screw H] which isslidable in the member It in the direction of movement of the member ll.In order to focus the optical system the slotted head I8 is rotated inthe proper direction and the member I! together with the optical systemi3 is bodily moved toward or away from the film. When the system is inproper focal adjustment the cap screw I9 is tightened thereby firmlysecuring the member H to the member I6.

of the screw in the slot 26. The member l6is' precluded from lateralmovement which would tend to throw the optical system out of adjustmentby means of the pins'Z'l and 28 which are pressed into the member l5 andthe ends of which fit into the keyways 29 and 30 in the bracket [6. Acap screw 3| is provided which is threaded into the member l5 and whichfits into an enlarged light from the film to the photocell, said opticalsystem being mounted on a bracket, said bracket being adjustable formovement of the optical system laterally of the film, the adjustingmeans for said bracket including pins in a fixed member cooperating withkeyways in said bracket for maintaining the bracket in alignment, ascrew for moving said bracket along said keyways, and a screw forclamping said bracket tosaid fixed member.

2. In a sound reproducing apparatus including means for moving a filmpast a translation point,

hole in the member l6 permitting movement'of the member l6 for lateraladjustment. After the adjustment is completed by means of the screw 25the cap screw 3| is tightened thereby securing the member l6 rigidly tothe member 15.

Having now described my invention, I claim:

1. In a sound reproducing apparatus including means for moving a filmpast a translation point, means for directing light through the film,

.and a photocell adapted to receive light passing through the film, anoptical system for directing means for directing light through the film,and a photocell adapted to receive light passing through the film, anoptical system for directing light from the film to the photocell, abracket supporting said optical system, means for adjusting said opticalsystem toward and away from said film on' said bracket, said adjustingmeans including a cam and a screw locking means, said bracket beingadjustable for movement of the optical system laterally of the film, theadjusting means for said bracket including pins in a fixed membercooperating with keyways in said bracket for maintaining the bracket inalignment, a screw for moving said bracket along said keyways, and ascrew for clamping said bracket to said fixed member.

JOHN F. WEIN.

